1. Field of the Invention
The present invention relates to the field of Wireless Local Area Networks (WLANs). More particularly the invention relates to an Access Point (AP) in a WLAN, a method for selecting a channel for an access point (AP) and a method for assisting the AP in selecting a channel.
2. Description of the Related Art
The deployment of WLANs based on the 802.11 standard has increased dramatically in the past few years. For the purpose of occupying the market and providing seamless coverage, multiple service providers independently deploy WLANs in the same range, and moreover each deployment involves multiple Access Points (APs). The APs based on the 802.11a standard are rarely seen in the market due to transmission distance problems and incompatibilities with the 802.11b standard. Other Access Point supported standards such as 802.11b and 802.11g can only support three non-overlapping transmission channels (i.e., channel 1, channel 6 and channel 11). As a result, a terminal always finds multiple APs operating on the same channel and within that terminal's sensing range.
As known by those skilled in the art, WLANs are based on a carrier sensing mechanism to share channels, which results in each terminal having to share channels with all APs and terminals operating on the same channel and within its carrier sensing range. The available bandwidth for each client is thus limited. There have been some alternative solutions for selecting a channel.
One manner is to monitor, by an AP, channels used by other APs, and then to select, by the AP, a channel where there are the fewest APs operating so as to reduce conflicts.
Another manner is to select, by the same service provider, different channels for APs deployed in the same coverage area. However, in the network environment as shown in FIG. 1, such manners for selecting a channel will have a negative impact on the service quality experienced by a terminal 110. For example, it is assumed that in the WLAN shown in FIG. 1, APs 101 and 102 are within the sensing range of terminal 110 and can provide services therefore. AP 101 and AP 102 are respectively out of each other's sensing range.
In the case of AP 101 selecting channel 1, AP 102 also selects channel 1 since it does not detect other APs in its sensing range. However, the terminal 110 can detect that there are two APs operating in channel 1. The terminal 110 will be interfered by signals sent on channel 1 by the other AP and thus its available bandwidth will be reduced, regardless of AP 101 or AP 102 providing a service thereto. However, both AP 101 and AP 102 will not change their own channels as neither of them can detect that they operate in the same channel.
For such a network environment, there is no appropriate solution in the related art.